In the field of work vehicles, particularly those vehicles which perform digging or loading functions such as excavators, backhoe loaders, and front shovels, a work implement is generally controlled by a manual control system having two or more operator control levers, and additionally, other vehicle control devices. Typically, the manual control system often includes foot pedals as well as hand operated levers. A backhoe manufactured by J. I. Case Manufacturing Co., for example, employs three levers and two pedals to control the work implement. A backhoe manufactured by Ford Motor Co. utilizes four control levers. There are drawbacks associated with these implement control schemes. One is operator stress and fatigue resulting from having to manipulate so many levers and pedals. Further, a vehicle operator is required to possess a relatively high degree of expertise to manipulate and coordinate the control levers and foot pedals proficiently. To become productive, an inexperienced operator also requires a long training period to be familiar with the controls and their functions.
Some manufacturers recognize the disadvantages of having too many controls, and have adopted a two-lever control scheme as the norm. Generally, two vertically mounted two-axis levers share the task of controlling the movement of the work implement's appendages (boom and stick) and the bucket of the work implement. For example, hydraulic excavators presently manufactured by Caterpillar Inc. employ one joystick for stick and swing control, and another joystick for boom and bucket control. Similarly, Deere & Co. has a hydraulic excavator with a joystick for boom and swing control, and another for stick and bucket control. In each instance, the number of controls has decreased to two, making machine operation much more manageable. However, these two-lever control schemes are still not wholly desirable. The assignment of implement linkages to the joysticks is entirely arbitrary, and there exists little correlation between the direction of movement of the work implement linkages and those of the control levers.
Further, in a typical leveling operation (or slope finish) the operator has to manipulate the control levers about or along at least three axes to produce a linear movement of the bucket. The complexity and skill involved increase when performing these types of operations, thereby increasing operator fatigue and required training time.
The present invention is directed to overcoming the problems set forth above.